V8 Tapping when warm

Hi all

I have recently rebuilt a 3.5 V8. Sounds lovely on start up, but then as it warms up, you can gradually hear the tapping coming and getting louder until its at its loudest when fully warmed.

It sounds like just one noisy tappet.

Anyone have any ideas why it would do it when warm ?

Your thoughts would be appreciated.

Many thanks

Could be a number of things.
Did you check lifter pre-loads, if its a new cam was it bed in properly?
Are they standard lifters or has someone sold you bleed down lifters.

If it's just one lifter it could be a bad lifter. I've had it before. Annoying because it's not quick to replace.

To start with is the noise at valve gear or piston speed? I'm sure many will know what I'm thinking but liner problems are extremely rare on a 3.5, let alone one that's just been rebuilt.

My guess is a tappet if its knocking at the right speed

Thanks for all your replies. Id put money on it being a tappet, maybe faulty from new, but if it is this, how/ why would it do it when warm. You can hear it gradually coming after about a minute of start up, and gets louder as the engine warms up.

Are the rockers and shafts new ?

Exhaust manifold bolts stretch and come loose easily. When I bought my last rangie and got it for a score thinking that the tappets needed doing only to find out that the manifolds were loose...

Thanks for your thoughts V8Mitch, but I've checked them a million times, I so want it to be something simple. Looks like the inlet manifolds going to have to come off.

i read on another forum that you can get this sound if the oil feed / pressure is not what it should be, There was debate about different oil grades and pump effectiveness.
Then someone (who seemed to have years of experience) suggested checking the oil feed pick-up pipe (in the sump) for debris or fitting.
The guy who had the fault found his pick-up pipe was in fact not attached properly. He corrected this and reported the noise has now gone.
Worth a try?

Here's the other forum posts on this:
Help V8 engine oil presure problem - Discovery Forum - LR4x4 - The Land Rover Forum

I'm a newbie here guys to this site but I have a 2000 discovery 2. It has the 4 ltr engine in it and it's doing the very same thing. Start it cold and it's nice and quiet but after a short time I get a lifter tick from the back leafy side. Once it warms up it gets louder as well. I was thinking it's a lifter tht bleeds down as you can shut it off and wait a short while , restart it and it's quiet for a short time then starts ticking again. I would like to repair it myself but I'm new to the landy world and need some help on finding some info on how and wht is required to do that. If you know of some please let me know. Thankyou

The only thing I haven't replaced in the rebuild is the rockers and shafts eightinavee.

They didn't appear to be worn which is why I didn't change them, but maybe something is.

I have ran it with the rocker covers off, and couldn't really identify anything/obvious noise.